Collembola species composition and diversity effects on ecosystem functioning vary with plant functional group identity     

Nico Eisenhauer  Alexander C.W. Sabais 《Soil biology & biochemistry》2011,43(8):1697-1704

The relationship between decomposer diversity and ecosystem functioning is little understood although soils accommodate a significant proportion of worldwide biodiversity. Collembola are among the most abundant and diverse decomposers and are known to modify plant growth. We examined the effects of Collembola species diversity (one, two and three species belonging to different life history groups) and composition on litter decomposition and the performance of plant communities (above- and belowground productivity) of different functional groups (grasses, forbs and legumes). Collembola densities did not increase with diversity indicating niche overlap. Generally, Collembola species composition was a better predictor for ecosystem functioning than Collembola species number with the impacts of Collembola diversity and composition on ecosystem functioning strongly depending on plant functional group identity. Non-linear effects of Collembola diversity on litter decomposition and plant productivity suggest pronounced and context dependent species interactions and feeding habits. Net surface litter decomposition was decreased by Collembola, whereas root litter decomposition was at maximum in the highest Collembola diversity treatment. Forbs benefitted most from the presence of three Collembola species. Similarly, Collembola diversity influenced root depth distribution in a plant functional group specific way: while grass root biomass decreased with increasing Collembola diversity in the upper and lower soil layer, legume root biomass increased particularly in the lower soil layer. Idiosyncratic and context dependent effects of Collembola diversity and composition even in rather simple assemblages of one to three species suggest that changes in Collembola diversity may have unpredictable consequences for ecosystem functioning. The finding that changes in Collembola performance did not directly translate to alterations in ecosystem functioning indicates that response traits do not necessarily conform to effect traits. Distinct plant functional group specific impacts of Collembola diversity on root depth distribution are likely to modify plant competition in complex plant communities and add a novel mechanism how decomposers may affect plant community assembly.  相似文献   

Functional electrical stimulation of the left recurrent laryngeal nerve using a vagus nerve stimulator in a normal horse     

Katleen Vanschandevijl  Heidi Nollet  Kristl Vonck  Rorecht Raedt  Paul Boon  DirkVan Roost  Ann Martens  Piet Deprez 《Veterinary journal (London, England : 1997)》2011,189(3):346-348

The aim of this study was to assess the feasibility of implanting an existing vagus nerve stimulating (VNS) electrode around the recurrent laryngeal nerve. The stimulus response characteristics required to achieve abduction of the ipsilateral arytenoid by the VNS electrode in the normal horse could then be determined. The electrode was wound around the left recurrent laryngeal nerve at the cervical level and connected to a pulse generator. Stimulus response characteristics were obtained by measuring stimulated arytenoid displacement endoscopically in the standing, non-sedated horse. A full and sustained abduction of the arytenoid was obtained with a stimulation frequency of 25 Hz and intensity of 1 mA with a pulse width of 250 μs.  相似文献   

Idiopathic Dilated Cardiomyopathy in Dogs: Survival and Prognostic Indicators   总被引：1，自引：0，他引：1  

Eric Monnet  E. Christopher Orton  Mo Salman  June Boon 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1995,9(1):12-17

To further define the prognosis and identify clinical findings predictive for survival in dogs with dilated cardiomyopathy (DCM), we performed Kaplan Meier survival analysis of 37 dogs with idiopathic DCM. Survival analysis showed that the 50% probability of survival occurred at 2.3 months. Probability of survival at 1 year was 37.5% and at 2 years was 28%. Bivariate Cox proportional hazard ratios identified pleural effusion and pulmonary edema, both signs of congestive heart failure, as independent prognostic indicators for dogs with DCM ( P < .01). Hazard ratios for these prognostic indicators were 2.354 and 3.291, respectively. Multivariate Cox stepwise regression identified pleural effusion, left ventricular free-wall thickening fraction, ventricular ectopy, and weight loss as significant prognostic indicators for dogs with DCM. Because of the retrospective nature of this study, the effects of different drug treatments were not evaluated. The type of cardiac-related death, progressive failure versus sudden death, was not addressed in this study and requires further evaluation.  相似文献   

A sero-epidemiological survey of infections with the bovine respiratory syncytial virus in first-season grazing calves     

H W Ploeger  J H Boon  C H Klaassen  G van Florent 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1986,33(4):311-318

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Physiological effects of experimental verminous bronchitis in Friesian calves.          下载免费PDF全文

P Lekeux  R Hajer  J H Boon  M W Verstegen    H J Breukink 《Canadian journal of veterinary research》1985,49(2):205-207

Pulmonary function values were measured in five Friesian calves of five months of age during the patent phase of an experimental moderate lungworm infection and were compared with the pulmonary function values recorded in four control animals. All the nine calves were free of any previous challenge with Dictyocaulus viviparus and were submitted to the same standardized conditions of body conformation, housing, feeding and procedures for pulmonary function testing. A significant increase of respiratory rate, minute ventilation, total pulmonary resistance and power of breathing and a significant decrease of tidal volume, dynamic lung compliance and PaO2 were observed in the infested animals. The absolute intrapleural pressure values were also significantly more negative. The conclusions of the statistical analysis were almost identical when predicted instead of measured pulmonary function values were used in the control group. The clinical, functional and pathological findings in the infested animals were all consistent with the picture of a lower airway obstructive disease.  相似文献   

Echocardiography for the diagnosis of congenital heart defects in the dog     

W E Wingfield  J A Boon 《Veterinary Clinics of North America: Small Animal Practice》1987,17(3):735-753

Echocardiography utilizing M-mode and real-time techniques is a safe, noninvasive diagnostic technique for use in veterinary cardiology. It provides a means to assess structural sizes and relationships and can be used to provide quantitative data for diagnosis of congenital heart disease. Although its availability is largely limited to veterinary colleges and specialty hospitals, the practicing veterinarian should know of its advantages and disadvantages. He or she is also encouraged to consider the use of ultrasound in the diagnosis and management of heart disease in all species of veterinary patients.  相似文献   

M-mode echocardiographs of endurance horses in the recovery phase of long-distance competition   总被引：1，自引：0，他引：1  

J J Bertone  K S Paull  W E Wingfield  J A Boon 《American journal of veterinary research》1987,48(12):1708-1712

M-mode echocardiographic structures, and cardiac function indices, PCV, and total plasma protein values were determined for 34 endurance equine athletes before (base line) and after (after race) a 161-km endurance competition and were compared. The PCV (base-line mean, 37%; after-race mean, 46%) and total plasma protein value (base-line mean, 6.9 g/dl; after-race mean, 7.5 g/dl) increased. Compared with base-line echocardiography, after-race echocardiography indicated an increase in heart rate, as determined from the simultaneous ECG recorded on the echocardiograph (base-line mean, 41 beats/min; after-race mean, 54 beats/min), and an increase in interventricular septal diastolic thickness (base-line mean, 28 mm; after-race mean, 33 mm). The septal thickening fraction (base-line mean, 59%; after-race mean, 38%), the left atrioventricular valve E to F slope (base-line mean, 224 mm/s; after-race mean, 175 mm/s), the left ventricular diastolic dimension (base-line mean, 99 mm; after-race mean, 86 mm), the fractional shortening of the left ventricle (base-line mean, 41%; after-race mean, 37%), the aortic root dimension (base-line mean, 63 mm; after-race mean, 58 mm), the caudal aortic wall excursion (base-line mean, 19 mm; after-race mean, 11 mm) and the left atrial diastolic dimension (base-line mean, 46 mm; after-race mean, 39 mm), decreased significantly (P less than 0.05). In base-line echocardiographs, late diastolic left atrioventricular valve motion was evident in 9 horses. The aberrant left atrioventricular valve motion was not evident in after-race echocardiographs. Seemingly, central vascular volume decreased in these horses during the recovery phase of severe strenuous endurance competition.  相似文献   

Effect of infections with swine fever virus on immune functions I. Response of lymphocytes from blood and lymphoid organs from infected and normal pigs to anti-immunoglobulin serum and protein A     

Jan T. Van Oirschot  Dirk de Jong  Nico D.N.H.J. Huffels 《Veterinary microbiology》1981,6(1):41-57

Pigs exposed to a low-virulent strain of swine fever virus (SFV) developed an inapparent infection. At times when a transient leucopenia occurred, the peripheral blood lymphocytes (PBL) were unresponsive to the mitogenic stimulus of anti-immunoglobulin serum (anti-Ig) and protein A.Pigs lethally infected with a virulent SFV showed leucopenia and unresponsiveness of PBL to anti-Ig and protein A from 2 days post infection until death.This suggests a defect in B lymphocyte function in pigs infected with SFV. The unresponsiveness to anti-Ig appeared not to be caused by a reduced ability of lymphocytes to redistribute their receptors into caps, the presence of suppressor cells or absence of surface immunoglobulin bearing lymphocytes in the peripheral blood. A direct action of the virus itself also seemed unlikely.Lymphocytes from spleen reacted as PBL. However, lymph node cells did not lose their capability to respond to anti-Ig.These data suggest that a change in the migration pattern of anti-Ig responsive lymphocytes could account for the observed unresponsiveness of PBL and spleen lymphocytes to anti-Ig.  相似文献   

Heterotopic implantation of a porcine bioprosthetic heart valve in a dog with aortic valve endocarditis     

Arai S  Wright BD  Miyake Y  Boon JA  Orton EC 《Journal of the American Veterinary Medical Association》2007,231(5):727-730

CASE DESCRIPTION: A 5-year-old male German Shepherd Dog was evaluated because of a 5-month history of progressive lethargy, weight loss, and heart failure. CLINICAL FINDINGS: On physical examination, bounding femoral pulses and systolic and diastolic murmurs were detected. Echocardiography revealed severe aortic valve insufficiency (AVI) and a large vegetative lesion on the aortic valve consistent with aortic valve endocarditis. The AVI velocity profile half-time was 130 milliseconds; the calculated peak systolic pressure gradient across the aortic valve was 64 mm Hg. Left ventricular diameter during diastole was 63.6 mm (predicted range, 40.2 to 42 mm) and during systole was 42.9 mm (predicted range, 25.4 to 27 mm). Systolic, diastolic, and mean arterial blood pressures were 120, 43, and 65 mm Hg, respectively. TREATMENT AND OUTCOME: To palliate severe AVI, the descending aorta was occluded (duration, 16.75 minutes) and heterotopic implantation of a porcine bioprosthetic heart valve in that vessel was performed. After surgery, systolic, diastolic, and mean arterial blood pressures were 115, 30, and 61 mm Hg, respectively, in the forelimb and 110, 62, and 77 mm Hg, respectively, in the hind limb. Within 6 months, the AVI velocity profile half-time had increased to 210 milliseconds, indicating diminished severity of AVI. After 24 months, the dog was able to engage in vigorous exercise; no pulmonary edema had developed since surgery. CLINICAL RELEVANCE: Heterotopic bioprosthetic heart valve implantation into the descending aorta during brief aortic occlusion appears feasible in dogs and may provide substantial palliation for dogs with severe AVI.  相似文献   

An antigenic peptide produced by peptide splicing in the proteasome     

Vigneron N  Stroobant V  Chapiro J  Ooms A  Degiovanni G  Morel S  van der Bruggen P  Boon T  Van den Eynde BJ 《Science (New York, N.Y.)》2004,304(5670):587-590

CD8 T lymphocytes recognize peptides of 8 to 10 amino acids presented by class I molecules of the major histocompatibility complex. Here, CD8 T lymphocytes were found to recognize a nonameric peptide on melanoma cells that comprises two noncontiguous segments of melanocytic glycoprotein gp100(PMEL17). The production of this peptide involves the excision of four amino acids and splicing of the fragments. This process was reproduced in vitro by incubating a precursor peptide of 13 amino acids with highly purified proteasomes. Splicing appears to occur by transpeptidation involving an acyl-enzyme intermediate. Our results reveal an unanticipated aspect of the proteasome function of producing antigenic peptides.  相似文献